Is there a limit to the number of keywords that can be added to a campaign?

Campaign Keyword Limit

There is a maximum limit of 1000 keywords per campaign in order to ensure efficient report generation and convenient viewing. Adding more than 1000 keywords to a campaign will cause some functionality to be disabled.

If you need to track more than 1000 keywords for a site, then best practice is to create additional campaigns (e.g., separate them by keyword category, location, tags, etc.). If you have an Enterprise package, you can view rank performance data for multiple campaigns in the Portfolio Report and by using cross-campaign metrics in the Insight Graph and Single Metric Widgets.